The present invention relates to etching an etch layer through a mask during the production of a semiconductor device. More specifically, the present invention relates to etching a dielectric layer through a line-space patterned mask during the production of semiconductor devices.
During semiconductor wafer processing, features of the semiconductor device are defined in the wafer using well-known patterning and etching processes. In these processes (photolithography), a photoresist (PR) material may be deposited on the wafer and then is exposed to light filtered by a reticle. The reticle may be a transparent plate that is patterned with exemplary feature geometries that block light from propagating through the reticle.
After passing through the reticle, the light contacts the surface of the photoresist material. The light changes the chemical composition of the photoresist material such that a developer can remove a portion of the photoresist material. In the case of positive photoresist materials, the exposed regions are removed, and in the case of negative photoresist materials, the unexposed regions are removed. Thereafter, the wafer is etched to remove the underlying material from the areas that are no longer protected by the photoresist material, and thereby produce the desired features in the wafer.
A vertically straight feature profile is necessary to maintain device yield. However, there are several mechanisms to cause deviations from the vertically straight profile: bowing refers to widening in the upper-middle portion of the feature; necking refers to narrowing near the top of the feature; tapering refers to narrowing towards the bottom of the feature; and twisting refers to random deviation of the position and orientation at the bottom of the feature or the distortion of the bottom shape, leading to misalignment to the underlying active devices.
As the integrated circuit dimensions shrinks, the critical dimensions (CDs) and profile control in high aspect ratio feature etching becomes very challenging problem in dielectric etch. Eliminating or reducing profile bowing (bow protection) in vertical profiles is one of such challenging problems. High-aspect ratio (HAR) line-space features have a high ratio of opening depth to opening width. A mask, such as a photoresist mask and/or a hard mask, is used to provide such a line-space pattern. In the specification and claims, a high aspect ratio feature is defined as a feature with a depth to space ratio greater than 10:1.